Electron discharge device anode fin insert with integral radiating wings



Feb. 18, 1969 c. DROPPA 3,428,344

ELECTRON DISCHARGE DEVICE ANODE FIN INSERT WITH INTEGRAL RADIATING WINGS Filed Sept. 9, 1966 IN VEN TOR. CY/m .DRoPPA F51 5 ywijliw/ United States Patent 3,428,844 ELECTRON DISCHARGE DEVICE ANODE FIN INSERT WITH INTEGRAL RADIATING WINGS Cyril Droppa, Emporium, Pa., assignor to Sylvania Electric Products Inc., a corporation of Delaware Filed Sept. 9, 1966, Ser. No. 578,299 US. Cl. 31339 4 Claims Int. Cl. H01j 1/46, 61/52; H01k 1/58 ABSTRACT OF THE DISCLOSURE An electron discharge device having a cathode and a grid is provided with an anode surrounding the cathode and grid electrode. By providing a heat dissipating means projecting inwardly from the anode to a point closer to the cathode than any part of the anode improved heat dissipating capabilities are achieved, thereby enhancing the operating characteristics of the device.

This invention relates to electron discharge devices and more particularly to heat dissipating means formed for incorporation into such devices.

Excessive heat generated at the anode is a problem in many types of electron discharge devices. Generally, this problem becomes particularly acute whenever a high positive potential is applied to the anode. This is especially true of the devices known as beam power tubes. These tubes are designed for high power applications and are useful in many types of circuits, e.g., the deflection circuits in television receivers.

In the past it has been the practice to add heat radiating fins to the anode to assist in the dissipation of heat and thus allow higher anode potentials to be utilized. While this practice achieved some degree of success with certain types it is not particularly applicable to beam power tubes.

In beam power tubes the anode is comprised of anode halves joined together along a parting line. Positioned between the anode halves and projecting inwardly toward the cathode is a fin which is employed to raise plate current, reduce screen current and produce a more acceptable plate to screen current ratio. The fin may also be used in conjunction with other tube design features to reduce or eliminate snivets by providing a lower knee voltage.

Because of its proximity to the cathode a considerable portion of the plate current flows to the fin. The resultant heat, which is generated in the fin due to normal electron conduction, is very high. Heat transfer in these designs depended upon surface contact between the fins and the anode halves and thus it will be seen to vary with the uniformity of the parts, the smoothness of the surfaces, the area of contact, and the number of stakes or welds used to join the parts. Because the contact between these pieces is not uniform localized hot spots develop in the fins and anode halves. Further, heat that is transferred from the fins to the anode halves is only partially effective in cooling the tubes since some of the heat is radiated back into the tube thus elevating the temperatures of the internal electrodes. Excessive temperatures are a major cause of beam plate emission, and grid emission which deleteriously affects tube performance and contributes to poor life characteristics.

In tubes designed without fins the anode itself is often formed inwardly toward the cathode at some portion or another. In these tubes uneven heating again results since that portion of the anode closest to the cathode is being heated directly by electron conduction and thus is hotter than other parts of the anode. Inability to dissipate this excessive heat rapidly also deleteriously affects tubes of this type.

3,428,844 Patented Feb. 18, 1969 "Ice Therefore, it is an object of this invention to enhance the heat dissipating capabilities of electron discharge devices.

It is another object of the invention to obviate the above-described disadvantages.

It is still another object of the invention to reduce unwanted secondary emission in electron discharge devices.

These and other objects are accomplished in one aspect of the invention by the provision, in an electron discharge device having a cathode and at least one grid, and an anode surrounding the cathode and grid of heat dissipating means formed to project inwardly of the anode to a point closer to the cathode than any part of the anode and which has integrally formed means thereon which project outwardly from the anode to form heat radiating wings.

Tubes constructed according to the above provide considerably greater heat dissipation than those used heretofore. By placing the heat dissipating means closer to the cathode than the anode it absorbs and transfers more heat than the anode. Further, the provision of heat radiating wings integrally formed on the heat dissipating means provides a completely conductive heat path from the inside of the electrode cage to the outside. This system is much more efficient than prior art constructions which utilized partly conduction and partly radiation to cool the tube. The elimination of the hot spots at the jointure of the heat dissipating means and the anode and the better cooling contribute to longer life and much improved operating characteristics.

For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the accompanying drawing in which:

FIG. 1 is a sectional plan view of an electron discharge device incorporating an illustrative example of the invention; and

FIG. 2 is an alternate form of the invention.

Referring now to the drawings with greater particularity in FIG. 1 there is shown an electron discharge device 10 of a type known as a beam power tube. The device 10 is comprised of a glass envelope 12 and an electrode cage 14 which is positioned between a pair of insulating means 16, only one of which is shown.

The electrode cage is comprised of: a cathode 18 having an electron emissive coating 20 thereon; grids 22, 24; beam confining plate 26; anode 28; and heat dissipating means 30.

The anode 28 is comprised of anode halves 32 and 34 having, respectively, end walls 36, 38.

Oppositely disposed side walls 40 and 42 project from end wall 36 and are formed to provide outwardly extending longitudinal joining flanges 44 and 46 at the portion thereof remote from end wall 36. Likewise, oppositely disposed side walls 48 and 50 project from end wall 38 and are formed to provide outwardly extending longitudinal joining flanges 52 -and 54 at the portion thereof remote from end wall 38.

Heat dissipating means 30, of which there are two in this instance, are formed to provide a substantially U- shaped fin 56 which is formed so that the closed end of the U lies within the anode. In tubes that do not have a fin but have a portion of the anode closer to the cathode than other portions the heat dissipating means may be integrally attached to the closer portion of the anode by any suitable means, such as welding. It is also to be noted that other configurations than U shaped may be utilized for the fin; for example I shaped. The upright leg portions 58 of one of the fins 56 are engaged by the longitudinal joining flanges 44, 52; i.e., one from each of the anode halves 32 and 34, and the upright leg portions 58 of the other fin 56 are engaged by the longitudinal joining flanges 46, 54. The jointure between these legs and flanges may be made by any conventional technique such as staking or welding. The legs 58 of U-shaped fins 56 project beyond the joining flanges and are formed to provide heat radiating wings 60. In the embodiment shown these wings extend at substantially right angles to the legs and parallel to the anode side walls; however, other angles may be used provided that the wings do not converge toward the anode side walls since this would tend to form heat pockets and deleteriously affect the operation of the device.

In FIG. 2 is shown an alternate construction. The fin 62 shown here is known as a Cavitrap and in this instance is formed of two sections 64 and 66 each of which has an integrally formed heat radiating wing 68 and 70, respectively. This integral consrtuction allows excellent heat conduction from the tin area to the heat dissipating means and provides greatly improved tube operation.

There is thus provided by this invention an electron discharge device having heat dissipating capabilities far beyond those of the prior art. These capabilities arise from the continuous heat conductive path from the interior of the electrode cage to the exterior. By virtue of this improved heat dissipating technique the temperature of the internal electrodes is lowered which thereby reduces secondary emission and greatly enhances the operating characteristics of the device. Similarly, these reduced temperatures increase the life expectancy of the tube.

It is to be noted that the particular form of fin shown here is by example only and that other configurations are possible. For example, the inwardly projecting fin 56 might be formed as a contiguous part of the anode and projecting heat radiating wings might be welded thereto, this construction also providing a continuous heat conducting path from interior to exterior.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In an electron discharge device having a cathode and at least one grid and an anode having end walls and laterally extending side walls surrounding said cathode and said grid the improvement comprising: heat dissipating means formed to project inwardly of said anode beyond said laterally extending side walls to a point closer to said cathode than any part of said anode side walls and integrally formed means thereon which project outwardly from said laterally extending anode side walls to form heat radiating wings.

2. The device of claim 1 wherein said outwardly projecting heat radiating wings extend for a given distance from said anode side walls in a direction substantially normal to said anode side walls and have outer portions which are bent to form a substantial angle with said normal.

3. The device of claim 1 wherein said anode is formed of anode halves each comprised of an end wall and two oppositely disposed side walls contiguous therewith, said side walls being formed to provide outwardly extending longitudinal joining flanges at the portion thereof remote from said end Wall; and wherein said heat dissipating means comprises a substantially U-shaped fin which is formed so that the closed end of the U lies within the anode, the upright leg portions of the U are in engagement with two of said longitudinal joining flanges of said anode, one from each half; and said upright legs of said U extend beyond said flanges and are formed to provide said heat radiating wings extending substantially parallel to said side walls of said anode halves.

4. In an electron discharge device having a cathode and at least one grid and an anode surrounding said cathode and said grid the improvement comprising: an anode formed of anode halves each comprised of an end wall and two oppositely disposed side walls contiguous therewith, said side Walls being formed to provide outwardly extending longitudinal joining flanges at the portion thereof remote from said end wall; and heat dissipating means comprising a substantially U-shaped fin which is formed so that the closed end of the U lies within the anode, the upright leg portions of the U are in engagement with two of said longitudinal joining flanges of said anode, one from each half; and said upright legs of said U extend beyond said flanges and are formed to provide said heat radiating wings extending substantially parallel to said side walls of said anode halves.

References Cited UNITED STATES PATENTS 2,957,999 10/1960 Gaylord 313 40 X 3,151,265 9/1964 Stephens 313-356 3,304,453 2/1967 Dlougy 313 40 JOHN W. HUCKERT, Primary Examiner.

R. F. POLISSACK, Assistant Examiner.

U.S. Cl. X.R. 

